Low RPM in gear under load, neutral is now fine - Fixed!

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Cuba660
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Low RPM in gear under load, neutral is now fine - Fixed!

Hello all. I'm experiencing some issues after a water in fuel tank drama, not sure if this new issue is connected to that but here's what's going on.
I have a 1994 Catalina 36 with the Universal M35A with 1750 hours.
Issue: Low RPM at Wide Open Throttle (WOT) in neutral and in gear underway. In neutral I can only get 2800 RPM WOT. In gear underway I only get 2100 RPM, and can hit 6.7 knots. I recall being able to attain 3100+ RMP and 7+ knots underway at WOT. The RPM at idle is 850, runs slightly rougher that before, if I bump the throttle slightly to 900 -950 it runs very smooth, apart from not reaching full RPM the engine runs smooth, no smoke, odd noises or vibrations and temp is fine.
Something interesting: Once I reach 2100 RPM in gear and underway, or 2800 in neutral, I still have 1’ of throttle travel where I get no engine response during that dead zone, it’s almost like the engine is governed, no change in RPM, sound, or vibration. This throttle dead zone is also noticed at the engine side where the cable attaches to the fuel control lever, the cable still has some travel before it hits the stop but the engine doesn't respond during that zone.
Recent history: I had water in fuel which lead to an engine out at near idle speed, I did not try to restart the engine after it stopped running. Fuel was removed and disposed of, the tank was polished, all fuel filters changed (RACOR, Main fuel filter, and Fuel Pump filter). I added fresh diesel and had the low and high pressure systems bled. When I took the boat out I noticed the low RPM issue, so I changed the RACOR and main fuel filter again and checked the fuel line that leads from fuel tank to RACOR for any blockage by blowing through the line, it seems fine. I also blew into the tank through pickup line in hopes of clearing any particles. Any fuel lines after the RACOR have not been checked yet. That’s as far I got. Not sure how old the fuel pump is, or if that would even cause this.
Looking through the forum there are a couple of things I still need to check, fuel pump pressure, RPM gauge calibration (less likely I'd think due to the throttle dead zone)
Thank you.
 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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pkeyser
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You may want to replace the 80 micron filter located on the bottom of the fuel pump (at least it is with the M35B). This filter  has a tendency to be overlooked and if it's never been changed, could certainly have accumulated some algae or other debris.

Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B

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alfricke
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You have done all the right things and something is definitely wrong. I hate to mention this, but one strong possibility is damage to the injectors or injector system. Since you have done all of the obvious things, very thoroughly, I'd want to run this by a good diesel mechanic. Keep us posted.

Al Fricke
S/V Jubilee San Francisco Bay
Catalina 36' MkII  #1867
Universal 35-B

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Cuba660
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Thanks. I have a good mechanic coming out to the boat. I'll let you know the result. 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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LeslieTroyer
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is your fan belt slipping??  The alternator is what drives the tach.  other than that - maybe a fouled prop

Les & Trish Troyer
Mahalo 
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor. 

Commodore

 

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Cuba660
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Thanks for the tip about checking the belt, I heard it slip once the other day. Here's what's going on so far. Mechanic came out and verified that the tach is not reading accurately. He mentioned the motor is running fine, he suspects a fouled prop. I'm doing a shorthaul next Wed.and I'm going to verify that the tach is off using a digital tach. Hoping its a dirty prop/shaft

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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Cuba660
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Thanks for the advice about the alternator belt, it was loose. Now I'm getting 3200 in neutral but still only getting 2100 in gear. I still have the issue where I have about 1 inch of throttle travel with absolutely not response, noise, etc from the engine, it stays a 2100 like it's governed. In neutral, I get full throttle response throughout the full range of travel, no dead zone. I'm starting to think is a fuel supply issue. I haven't been able to shorthaul to clean the bottom but I've dove down and cleaned the prop and shaft. This made no difference in RPM. I doubt it's a fouled bottom but I'm not sure. The 3/4 inch of dead throttle in gear I feel is the best clue in solving this. I've seems other threads where they talk about the fuel pump being the issue. I'll check the fuel pressure  next week to see what I'm getting. 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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pkeyser
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My bet would be the lift pump / fuel related issues too. I don't think a fouled bottom would have much impact- that would show up in boat speed, not engine RPM.

A spare fuel pump is a good thing to have on board. If that turns out not to be the problem, don't view it as a waste of $. 

I read of similar problems a while back. Maybe on this web site, I'm not sure. In one, the owner eventually discovered that the water separator fuel outlet had become clogged with algae growth. In the other, the fuel pump had failed but the tank on the MKII is slightly higher than the engine, so gravity was getting a partial fuel supply to the engine.

Paul & Wendy Keyser
"First Light"
Rye NH
2005 C36 MKII #2257
Wing, M35B

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Cuba660
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Thanks. Boat speed is down a bit, not too much, I agree this is probably not fouled bottom alone. I tested the fuel pressure with a gauge, it was reading a steady 7psi in neutral over a range of RPM between idle to 2000+. I didn't get a chance to test it under load so that might make a difference. Short-haul tomorrow so lets see if there's any improvement, I'm not getting my hopes up though. I'm betting pump or injectors. I'll let you know what I find
 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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Cuba660
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After short-haul, I can eliminate this issue being caused by fouled bottom, no surprise there. Next steps is looking deeper into fuel pump and injectors. Before I dive too deep into them, the Westerbeke manual says the "engine is governor controlled to prevent overspeed". Does anyone know where the govenor is on the M35A? In the troubleshooting part of the manual, under low rpms it mentions the govenor could be the issue. Any tips on the govenor appreciated.

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

rstonge
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Posts: 55

I have been having the same problem with loss of power for the last 10 to 15 years.   The first thing I did was to replace the exhaust riser with schedule 80 black pipe.  I did this about 10 years ago and it did help. 

Unfortunately,  things continued to deteriorate until last season at cruising RPM I was only getting about 5 knots.  I decided to bite the bullet and replaced the injectors.  This made a substantial improvement and now I can cruise at 6 knots.

When I first got the boat my WOT was 3200.  Before replacing the injectors it had dropped to 2500.  It is now 2800, so better but not all the way back.  

Ron St. Onge

1995 Catalina 36 MKII Hull 1384

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Cuba660
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I think I found the problem. I ran the motor and cracked open the fuel line to each injector one at a time. The first injector had no change in RPM, the other 3 had a noticeable difference in how the motor ran. That makes me think the first injector is not functioning. I may have them all inspected and cleaned. 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

C36CC
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Posts: 12

I am following your saga most intently. We have a 1993 with the M35A, 1760hrs. We're not sure what RPM we've been running at this season (our second season with our boat) because the tachometer has apparently been reading erratically the whole time and it also decided to not register above 1800rpm. We think we've been running much lower than normal cruise RPM as evidenced by our low boat speed this season even after having the bottom cleaned.  I got the handheld tach and learned that the readings on our boat tach are 400 RPM too high but have not had a chance to correct.  Also we're fighting a sporadic overheat problem, so have been reluctant to push her.  Anyway, TL:DR...today we set out and can't get more than maybe 1500rpm (can't be sure, handheld tach battery failed too) and ~3.5kt.  Planning to check/change fuel filters (Racor and @ fuel pump), check prop, etc.  Please post what you find with your injectors and I'll look at that too!  Good luck to both of us.

-Keith 
S/V Cool Change, City Island NY

1993 Catalina 36 Mk1.5, #1229, TR, WK

Universal M-35A

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Haro
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Posts: 364

I ran into this eratic RPM. It turned out to be a broken altetnator bracket. This will cause the belt to slip and show lower RPM.

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alfricke
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Posts: 80

I feel your pain. A couple of comments. 

Erratic or misleading tach RPM readings, caused by anything...including slipping alternator belt, are unlikely to be related to your problem. The actual engine RPM is what it is regardless of how fast the belt is moving. You can estimate RPM by the engine sound. Still, knowing your tach rpm is accurate is nice. 

I think the proper term is vacuum gauge, (not pressure) if you are referring to the Racor gauge. It is designed to give you an indicator of how hard the engine/lift pump has to pull to get fuel from the tank, and through the filter. It lets you know if there are restrictions "upstream" like clogged hoses, clogged intake, clogged vent, clogged filters (all prior to the gauge). Your reading of "7 psi" actually sounds high to me with new filters and all the work you have done to make sure the upstream is clear. That is right on the edge of marginal. There still could be fuel restrictions "downstream" like at the lift pump. 

I'm surprised your mechanic did not figure it out. I assume he replicated your problem at the dock? I can run Jubilee's engine in gear at the dock all the way up to 3K. 

It seems to me that if your engine will run to the proper max RPM in neutral, but will not when in gear (i.e. a load on it) that the problem is not enough fuel getting to it. I assume the mechanic inspected the injector system and gave it a clean bill of health? From what you have said, water did reach the injectors which can be disastrous. 

I'm not going to ask how the water got in the tank, but the designers who placed the water and diesel fillers right next to each other must never have owned a boat! Worse is when diesel is put in the water tank! That problem does not go away until the tank and all the freshwater plumbing hoses are replaced. No, it did not happen to me (but almost) but I know of someone who did this.

Finally, this is far out, but I assume you did not change props somewhere along the line? A huge high pitched prop would cause this symptom as well.

Keep the list posted as to your progress...I can see many others are wrestling with similar or related problems.
 

Al Fricke
S/V Jubilee San Francisco Bay
Catalina 36' MkII  #1867
Universal 35-B

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Cuba660
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Thank you for all the info above, it all makes sense. This weekend I think I found the problem. I ran the motor and cracked open the fuel line to each injector one at a time. The first injector had no change in RPM or motor sounds, the other 3 had a noticeable difference in how the motor sounded, the motor bogged down a bit. That makes me think the first injector is not functioning. This may be the blockage and why I'm getting higher pressure readings downstream of the fuel pump. A attached a low pressure gauge after the pump and engine mounted fuel filter, I put it right before the fuel manifold; this is where I got the 7psi reading. What are your thoughts on my injector test above? I've read that this is a good way to determine if an injector is not working.
Regarding my mechanic, he was convinced from the beginning that it was a fouled bottom, even after I told him about the lack of throttle response. I wasn't there when he checked the motor but I know he didn't try running the boat in gear at the dock. He did discover the low RPM issue being a loose belt but thats as far as he got. I'm somewhat disappointed that he didn't check the injectors. Again, your thoughts on the accuracy of my injector test (cracking each fuel line one at a time at each injector) would be very helpful. One last thing, do think it's safe to operate the motor with one bad injector? It's close to haul-out and I'm thinking about getting all my injectors check/cleaned once I'm on the hard. Thanks!

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

dhickmanii
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Posts: 26

I used this app on my iPhone  to calibrate my tachometer.  I found it easier to use than a digital handheld tachometer.  Also, it’s free .

https://apps.apple.com/us/app/strobe-tachometer-rpm-meter/id831460940

If you have never used a strobe light for measuring rotational speed, this website provides a pretty good explanation of the process. 

https://monarchserver.com/Files/pdf/Strobe%20for%20RPM.pdf

 

David
Mobile, AL
S/V Beach Belle
1983 Catalina 36 Mk I #154

Std. Rig, Fin Keel, M25

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Cuba660
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Thank you!

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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alfricke
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Posts: 80

Cuba....small thing first...if you go to your account-edit-signature...you can put in your name and boat name and model and hull# and engine type so it automatically is entered into your posts and we can see what you have.

Not sure of the value of a pressure gauge after the lift pump, except that it shows the pump is working. Vacuum gauge at the filter insures everything upstream is good. My gauge on the Racor 500 reads 1-2 at idle, 5 at max RPM (3000), and when I close the fuel valve at the tank enough to change the engine sound, it reads 7-8 ("yellow zone"). 

I carried spare injectors when we were doing long range cruising on bigger boats, but never had to use them. Injectors are the bread and butter of diesel mechanics...they scare me. 

I'm sure many on the list will be interested in how your problem finally gets resolved.

Al Fricke
S/V Jubilee San Francisco Bay
Catalina 36' MkII  #1867
Universal 35-B

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Cuba660
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Good point about sig block. I updated it. I'll put some info below just in case it doesn't show up right away.
I like the idea of adding a gauge to the RACOR, I see my RACOR housing has an extra Out port, I assume that's where it would go.
As far as upstream blockage, I removed the fuel shut-off valve that comes from the tank due to a fuel hose routing problem, I simply couldn't get to the valve the way it was positioned, so i plan to reinstall that as soon as I get back to the boat. To check if I had an issue with the fuel tank vent, I ran the boat with the fuel cap off for a second, assuming this would help reveal any vent issue, pure speculation but I thought it made sense. 
My test downstream was just to verify my fuel pump was putting out consistent pressure, so I feel like that's not the issue. I checked transmission temp underway (135 deg) and fluid level, all seemed good. I also checked the stuffing box temp underway (94 deg). Running out of things to check, I feel its at the motor end, starting with the injectors. Not sure my test of cracking the fuel lines at the injector is a solid injector test, but I had one that seemed like it wasn't working based on no change in motor sound/behavior. I'll keep everyone posted.

 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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LeslieTroyer
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Posts: 533

A lot of times the obstruction is in or on the end of the fuel pickup in the tank.  Gauge should go on inlet of your racor.  

Les & Trish Troyer
Mahalo 
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor. 

Commodore

 

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Cuba660
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Good point! I'll try that. Thank you

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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Cuba660
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Posts: 22

Issue resolved. See below if interested in what was causing my issue. This is a copy paste from a message to another owner that was having the same issue, so you'll notice the response talks a bit about torque values. I'm interested to hear if anyone has had the same issue with the fuel injector torque at 36 ft lbs like the manual suggests, my injector leaked fuel at that torque value. Anyway, here's the message:
 Fixed my problem! But first a note about the torque valve of the fuel injector, mine wouldn't seat well at 36ft lbs. it wouldn't seat at 45 ft lbs, it leaked fuel/air at the base of the injector. When I removed the old one, it was very tight, I mean tight. I'm not sure what it's torqued to now sine I got tired of removing all the lines etc to keep tightening it, I gave it a slight nudge past 45ft lbs. I'm not getting any fuel leaking from it now, just keep an eye on yours after you retorque it. Now, what fixed my low RPM issue, I don't think it was the fuel injector. While installing the new fuel injector I noticed the fuel line attached to the #1 fuel injector pump was loose, I didn't notice it before and didn't see the very small fuel leak because it was on the back of the nut. I tightened it up and replaced the #1 fuel injector which I thought was bad. During the installation I accidentally loosened the fuel line coming off the injector pump to #4 injector. I tightened it up snug. I ran the motor and I had the same issue with low RPM. So I did my test of breaking each fuel line loose at the injector. #1 made the motor bog down (I was happy knowing I at least  fixed that problem). I checked the other 3 injectors and now found #4 was not working....then I realized what has been going on this whole time, a loose fuel line at the fuel injector pump. I tightened the line to #4, bingo, it fixed the issue. So if you get the slightest bit of fuel in your motor area bilge, start looking because that little leak caused this issue for me. 

Cuba Gonzalez
S/V Joyita
Chesapeake Bay, Harrington Harbour South
1994 Catalina 36 MkII #1326
Universal M35A

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